Ghrrum
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DIY Vacuum insulated panels?
Somewhere between two places I decided I wanted to have a drink cooler in my van.
Now certainly, I could go to the local Big box store and I could get a plastic monstrosity that's got some foam insulation that'll do okay, or I can
carve out a kidney and sell it on the black market for one of the really fancy vacuum insulated yeti Coolers.
But why? I'm a nerd, I can do this.
So right now my brain is stuck on the idea of creating vacuums related panels with a 3D printed gyroid foam, essentially just a box of pla with gyroid
infill. Pla is apparently vacuum stable, so it should work as an insulating material provided it can withstand the external pressure.
So the only thing past that is figuring out how to wrap that in stuff and pull a vacuum on it. My initial thought was to use my big vacuum pump and
vacuum chamber which is not so big, and find some secret tape or sauce to have it seal after it pulls down the vacuum. I quickly realized that trying
to do this inside a vacuum chamber without something like a UV cure resin or similar special accessory that can be activated from outside the chamber
to affect stuff inside the chamber would be a b**** to do.
So I shelved the idea, well I have plenty of time to think on road trips, and in our number 6.5 of driving along I-40 somewhere in the middle of
nowhere North Carolina I had a brain wave. Vacuum food sealers, no granted those things are only pulling like four, maybe 5 in of Mercury. But what if
I put a vacuum pump on that or stuck that whole assembly in a vacuum chamber so the impulse sealer portion of it would function correctly to seal and
retain the vacuum after everything has been drawn down?
I need to try this.
Any thoughts or ideas on why this might be stupid? Any ideas on the bags that are commonly used with this not being suitable for that high of a vacuum
pressure?
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unionised
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I'd need to check, but I think that, if you didn't bother with a vacuum, the gyroid fill would conduct much more heat than the air.
Pulling a vacuum would hardly make a difference.
(And, btw, you need a really good vacuum to make much difference)
[Edited on 19-9-25 by unionised]
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chempyre235
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I have a hard time believing that PLA could withstand a decent vacuum. Additionally, 3D printed models won't be airtight, as seams between layers are
weak points for your print. There would have to be some kind of external sealant to pull a lasting vacuum. Also, PLA will eventually hydrolyze to
lactic acid, especially if it's exposed to light and water regularly. Lastly, you'd need a very large print bed (and a lot of filament) to print a
cooler panel that's more than (2) 12oz. cans wide.
As for the vacuum bags, I have no idea if this would work. Also, what kind of vacuum pump will you use? To my knowledge, the ones for the food sealers
don't get anywhere close to the pull you'd need.
"However beautiful the strategy, you should occasionally look at the results." -Winston Churchill
"I weep at the sight of flaming acetic anhydride." -@Madscientist
"...the elements shall melt with fervent heat..." -2 Peter 3:10
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Sulaiman
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for journeys of a few hours a common expanded polystyrene box with a few cold packs seems sufficient
but for longer car trips we often take a 12v cooler box along.
if you can accomodate one they are great.
this points to something similar....
https://www.ebay.co.uk/itm/363570346355
the ac mains option allows pre-cooling before the journey
and allows the cool box to be plugged into ac power wherever we stay.
They are inefficient, but I don't care 
you could diy one using modules like this, many options available.
https://www.ebay.co.uk/itm/386935237661
you could even diy using individual components, but it would cost more.
IF you do, I recommend the 12715 peltier modules but use at 6v for efficiency.
two in series are just nice for '12V' dc.
,............................
vacuum insulated walls are a nice idea, better than expanded polystyrene,
but I guess that more heat is lost due to multiple opening/closing operations 
CAUTION : Hobby Chemist, not Professional or even Amateur
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Ghrrum
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Quote: Originally posted by unionised  | I'd need to check, but I think that, if you didn't bother with a vacuum, the gyroid fill would conduct much more heat than the air.
Pulling a vacuum would hardly make a difference.
(And, btw, you need a really good vacuum to make much difference)
[Edited on 19-9-25 by unionised] |
Want to make sure that I'm being clear on my idea. I'm planning on using the plastic film that is normally used with food vacuum sealers over gyroid
infill. I'm aware that the plastic will conduct heat to an extent.
I am not using the PLA to hold the vacuum, I am using the PLA to create shape and the vacuum sealer film to hold the vacuum.
In regards to the vacuum being pulled I'll be drawing down to 28-29 inHg (about 0.9 Bar or 710 mmHg in science units). While this is not in the realm
of a turbo molecular pump, I feel like it is fairly respectable for vacuum pressure and enough to see a difference.
For clarity, the ultimate purpose of this is less the end result and more wanting to see if I can.
Further I can purchase commercial vacuum insulated panels used in commercial insulation for 30-40 USD each and I could use those to produce the cooler
I desire.
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Twospoons
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You wont hold a vacuum for long with plastic film. As far as I can tell all plastics are gas permeable to some extent - some more than others.
There's a good reason vacuum flasks are made from glass or metal.
And as has been pointed out, your gyroid infill will conduct heat. Simple back of the envelope calc would suggest that 20% infill would be about the
same conductivity as air
PLA: 0.13 W/(m.K)
air: 0.026 W/(m.K)
styrofoam: 0.029-0.040 W/(m.K)
Argon : 0.018 W/(m.K)
[Edited on 21-9-2025 by Twospoons]
[Edited on 21-9-2025 by Twospoons]
Helicopter: "helico" -> spiral, "pter" -> with wings
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Ghrrum
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| Quote: | | Quote: Originally posted by Twospoons | You wont hold a vacuum for long with plastic film. As far as I can tell all plastics are gas permeable to some extent - some more than others.
There's a good reason vacuum flasks are made from glass or metal.
And as has been pointed out, your gyroid infill will conduct heat. Simple back of the envelope calc would suggest that 20% infill would be about the
same conductivity as air
PLA: 0.13 W/(m.K)
air: 0.026 W/(m.K)
styrofoam: 0.029-0.040 W/(m.K)
Argon : 0.018 W/(m.K)
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Well, that's both incredibly helpful and disappointing. I'll have to rework my idea. I want the ability to do this because it seems like a fun
challenge.
I didn't pick up on the initial bit about the thermal conductivity being the problem and latched on to the idea that I had been unclear and somehow
conveyed that I was planning on using the PLA alone.
Now I need to determine what sort of foam is being used in vacuum insulating panels normally.
[Edited on 24-9-2025 by Ghrrum] |
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Ghrrum
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Still thinking on how to make it work.
So after a brief look around on Wikipedia I discovered that pearlite is one of the insulating foams used in commercial vacuum insulated panel
production.
That bodes well as I should, I think, replace the infill with pearlite and still get the ability to have a conformal shape with the insulating ability
I desire. Now the next step is figuring out the metal foil end of things, originally I was hoping to use some sort of plastic to reduce the difficulty
in sealing the panel, but it looks like that is not to be. Metal foil will have to be the material of choice.
Now, though I hope to be wrong, I suspect aluminum foil will not suffice for this purpose. As far as creating an envelope that will hold up for any
significant period of time it feels too delicate, specifically the off the rack rolls you can get at a grocery store.
So, alternative? Stainless steel foil, this stuff should hold up. My major consideration now is what closure method to use for the foil.
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Ghrrum
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https://www.sciencedirect.com/topics/engineering/vacuum-insu...
Jumping off from here it appears that the standard is a layer of aluminum vacuum deposited on PET, rinse and repeat a couple times and you have a
plastic like film that will hold the vacuum. The other plastic used in there is LLDPE, essentially being used as a hot glue to seal up the unit.
Expected service life on the commercial panels is somewhere around 8-10 years before the vacuum degrades to the point it's just insulation in a fancy
bag, though some vacuum remains.
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Morgan
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Long ago, I pumped up this ordinary PET bottle and it stayed very taunt for at least 13 years. I was only hoping for a few months. I had imagined
making a boat out of the bottles, and even sails. I could still stand on it.
https://www.pulse-jets.com/phpbb3/download/file.php?id=3644
As an aside, a 2 and 3 liter bottle respectively, over pressurized with dry ice.
https://www.pulse-jets.com/phpbb3/download/file.php?id=3645
https://www.pulse-jets.com/phpbb3/download/file.php?id=3646
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